What you eat ends up in your hair. Scientists in the US and Europe have used this basic idea to devise a sort of hair-based GPS tracking system. Law enforcement agencies are now using this technique to solve crimes. NOVA's Ari Daniel Shapiro reports.

What you eat ends up in your hair. Scientists in the US and Europe have used this basic idea to devise a sort of hair-based GPS tracking system. Law enforcement agencies are now using this technique to solve crimes. NOVA's Ari Daniel Shapiro reports.

What you eat ends up in your hair. Scientists in the US and Europe have used this basic idea to devise a sort of hair-based GPS tracking system. Law enforcement agencies are now using this technique to solve crimes. NOVA's Ari Daniel Shapiro reports.